When pregnancy is at week 2, you are likely to conceive. Immediately after sperm fertilizes the egg, the chromosomes from each of them combine to create your baby’s unique set of genes.
Even during the first days of pregnancy, your baby’s sex and genetic features will already be determined. This combined egg and sperm is called a zygote. Like a set of architect’s plans followed by a builder, your zygote will turn itself into a baby by the end of your pregnancy.
Around this time, another phenomenon sometimes happens, called ‘twinning ‘.This can happen in more than one way.
Identical twins are called monozygotic twins (from one zygote).In this case, one sperm fertilizes one egg, which divides to form two embryos. This results in genetically identical babies of the same sex.
Non-identical twins are called dizygotic twins (from two zygotes).In this case, two eggs are the winners of the race to ovulate. Once in the tube, two sperm fertilize these two eggs, and the resulting babies can be of the same or different sex. They resemble each other like siblings born from different pregnancies but are not identical.
Within 24 hours of conception, the fertilized egg or zygote will start dividing into multiple cells and traveling down the uterine tube.